Is there a story in all of literature - Jewish or non-Jewish - more dramatic and compelling than Megilat Esther? It has everything: danger, intrigue, hair-pin twists and plot curves, brave heroes and heroines, and a despicable 
King Shaul took pity on Agag, deciding to pay honor to the Amaleki monarch.
villain.

King Shaul took pity on Agag, deciding to pay honor to the Amaleki monarch.
villain. Haman ranks right up there with the most evil bad guys in history. Who else do you know that has been publicly booed by large and boisterous crowds for two millennia?
The Megillah refers to Haman as "Haman ha'Agagi." But if his evilness is a direct result of his being descended from Amalek, why not call him, "Haman ha'Amaleki"?
To answer, we must refer back to the story of Agag in the Haftorah of Shabbat Zachor. There, we read how King Shaul took pity on Agag, deciding to pay honor to the Amaleki monarch rather than abide by G-d's command to utterly wipe out that nation - man, woman, child, beast and king. It takes Shmuel to upbraid Shaul and execute Agag.
In similar fashion, the Jews of Persia decided to show honor to Haman, bowing obsequiously before him. Only Mordechai, a la Shmuel, would not demean himself.
It has always been extremely hard for Jews to act in a seemingly "ruthless" manner. We are rachmanim b'nei rachmanim, distinguished by our quality of mercy; prone to forgive and forget, and judge others favorably.
That's why "wiping out Amalek" is so difficult a mitzvah for us and it may be why HaShem repeats "remember" and "don't forget." Just telling us once won't suffice. We always look for the best in people and are optimistic in the darkest of times. We can't accept that anyone is beyond saving.
But Amalek is different; they are the exception that proves the rule, the litmus test of whether we will follow our own instincts or G-d's will. If overcoming our nature is a Torah value, then Amalek is the supreme challenge.
The criminal raised his hand in a Nazi salute and defiantly yelled, "Heil Hitler!"


The criminal raised his hand in a Nazi salute and defiantly yelled, "Heil Hitler!"

When I was a rabbi in Dallas, there was a shul defaced by a neo-Nazi, who also planned to put poison gas in the ventilation system. At his trial, he told the court how he had been abused as a child and made wrong choices in life. He begged for mercy and the chance to right his wrongs. I'd have bet that most of the Jews in that courtroom would have gone easy on him. But the judge didn't - he gave him the maximum sentence.
As that sentence was pronounced, the criminal raised his hand in a Nazi salute and defiantly yelled, "Heil Hitler!"
I later asked the judge what compelled him to act so strictly, to "throw the book" at this criminal.
"Don't you understand?" he said to me, "It's him or us."
Amalek, Agag, Haman, Hamas - the lesson remains the same.